The present invention relates to a method of producing an electric, electronic, optic and/or mechanical component in which the component substrate is given a three dimensional structure or shape and the substrate then further worked to build the component.
It has long been known to construct different types of components, such as sensors and mechanical units, with the aid of methods with which the base of the component is formed from silicon, quartz or some other more or less expensive material. In some instances, the material can be worked micromechanically so as to give the material certain three-dimensional forms or structures. These substrates are then processed by adding material to or removing material from certain areas, for instance areas that have been defined with the aid of lithographic techniques.
For reasons of a process/technical nature, traditional bases are almost always comprised of a circular disc of substrate material. Subsequent to working the disc micromechanically so as to form the three-dimensional structure, the disc can be subjected to such processes as lithographic processes, PVD processes (physical Vaporised Deposition), CVD processes (Chemical Vaporised Deposition), doping, ion-implantation, or various types of etching processes (ion, chemical, plasma etching processes, etc.) A desired result can also be achieved by combining two or more of these processes.
A disc of this nature is dimensioned to enable a plurality of components to be built up simultaneously on one and the same disc, which is then divided into respective components.
Some of the process steps require unprecedented precision while other process steps are less critical. The cost of passing a quartz or silicon disc through all process steps is very high, although because precision is very high the individual units can often be made small and therewith enable many units to be manufactured at one and the same time and therewith keep the price of each unit relatively low.
However, these conditions do not always apply, such as when certain physical measurements must be observed for instance. Examples in this respect are when a unit includes a connection for an optical fibre of specific measurements, sample volumes for chemical or biochemical analyses, optical path lengths for gas sensors, and so on.
In these cases, the combination of space-demanding or area-demanding functions and precision and process requirements can cause the cost of the final component to be relatively high in comparison with what the component achieves.
Many examples of components that are produced by subsequent treatment of a three-dimensional structure to form the component are known to the art.
The publication xe2x80x9cCombustible Gas Sensor Fabricated With 3D-Micro Technologyxe2x80x9d by Tsing Cheng, Landis and Gyr Corporation, Central Research and Development Lab., CH 6301 Zug, Switzerland, illustrates an example of how a sensor, a compact three-dimensional thermopile can be built by microtechnology.
The substrate used in this document is a silicon disc (FIG. 5a). A grating or a number of ridges is/are provided on the surface of the disc. The grating is provided with two mutually different conductors at mutually different oblique angles (FIG. 5c), thereby forming a number of mutually sequential junctions from one conductor to the other. This procedure results in a thermopile.
The publication also discloses the possibility of using a polyimide as material for building the three-dimensional structure (FIG. 5b).
It should also be mentioned that the publication xe2x80x9cMicrostructures and Replication Techniquesxe2x80x9d by Olle Larsson, Industrial Microelectronics Center (IMC), Stockholm, Sweden published in conjunction with a national conference xe2x80x9cMicro Structure Workshop 1996xe2x80x9d held in Uppsala, Sweden, Mar. 26-27, 1996, describes how micromechanically produced models can be replicated by creating a mould from the model and then producing a plurality of copies or replicas of the model with the aid of the mould. The document describes a number of different ways in which this can be achieved.
It should also be mentioned that Swedish Patent Applications 93 02051 9 and 95 00849 6 teach methods of replicating channels that are intended to hold samples for a biochemical analyser that is based on electrophoretic separation. These channels are comprised of passive components and the electric field required for an analysis is applied with the aid of external electrodes.
When taking into consideration the technical deliberations that a person skilled in this particular art must make in order to provide a solution to one or more technical problems that he/she encounters, it will be seen that on the one hand it is necessary initially to realise the measures and/or the sequence of measures that must be undertaken to this end, and on the other hand to realise which means is/are required in solving one or more said problems. On this basis, it will be evident that the technical problems listed below are highly relevant to the development of the present invention.
When considering the present state of the art, as described above, and when taking a starting point from a method of manufacturing an electric, electronic, electromechanical and/or mechanical component where the component substrate is given a three-dimensional structure or shape and the substrate then subjected to further treatment to form the component, it will be seen that a problem resides in realising how the costs of producing this three-dimensional structure for components that have high accuracy requirements regarding the dimensioning of the three-dimensional structure and where respective components are of such a large size that only one or a few components can be produced on each disc of traditional size, can be kept at a level which is reasonable in relation to what the component or components is/are able to achieve.
Another technical problem is one of realising how such manufacture can be achieved without needing to micromechanically work each individual component.
Another technical problem is one of realising how certain limitations that exist in traditional substrates, such as silicon and quartz substrates, can be overcome and how components that require substrate properties that do not exist in, for instance, silicon or quartz substrates can be manufactured with the precision required and at reasonable costs.
Still another technical problem resides in overcoming the prejudices that exist in traditional component manufacture with regard to the use of materials other than silicon and quartz in lithographic processes, metallising processes, doping processes, etching processes, etc.
Yet another technical problem is one of realising that in addition to said component other components and/or necessary conductor paths can be produced from a three-dimensional structure by subsequent processing of said structure.
Another technical problem is realising that a three-dimensional structure can be worked to provide mechanical parts, such as snap-fastener means, outwardly jutting parts or recesses by means of which said component can be fitted to a base structure, in addition to producing said component.
It will also be seen that a technical problem is one of realising how a micromechanically worked structure can be divided into a number of three-dimensional structures that are intended for subsequent working and that have precise dimensions.
Another technical problem is one of realising the manufacturing advantages and economic advantages that are afforded by transferring an exact, micromechanically manufactured three-dimensional structure in silicon or quartz to a plurality of three-dimensional structures in a polymeric material.
Another technical problem is one of adapting a method according to the present invention to the production of different specific components, such as thermocouples, pressure sensors, electro-optical coupling units for optical sensors or units combined with electric signal processing or the establishment of electric contacts.
With the intention of solving one or more of the aforesaid technical problems, the present invention takes as its starting point a method of producing an electric, electronic, optical and/or mechanical component where the component substrate is given a three-dimensional structure or shape and the substrate then processed or worked to form said component. In brief, instead of using a flat silicon plate, which may be disc-shaped, as a substrate structure, certain geometrical details necessary for the component are formed on a silicon or quartz plate by means of a micromechanical method, in accordance with the invention. These geometric details are then replicated on a polymeric plate, which may also be disc-shaped. This enables those costly process steps that need to be carried out at great precision to be restricted to steps in which such precision is most necessary. This short cut enables the costs of certain components to be kept at a low level and in other cases further complexities that would otherwise had been impossible to achieve can be added.
The three-dimensional structure formed by the geometrical details can be transferred from the silicon plate or quartz plate to the polymeric plate by shaping, such as moulding, pressing, extruding or embossing, against a die or mould.
With the intention of making the manufacture of a component more effective, it is proposed in accordance with the invention that the component is produced on a limited surface area or region and that electric conductor paths and/or further electric and/or electronic components are produced on this delimited surface area in the same way, thereby enabling surrounding parts necessary for the component to be integrated therewith.
It is also possible in accordance with the invention to produce mechanical parts, such as snap-fastener means, outwardly jutting parts and recesses, by means of which the components can be fitted to a substrate.
The present invention proposes two basic methods of enabling a three-dimensional structure to be replicated.
According to a first method, at least that part of the die or mould which corresponds to the component is produced by shaping said die to a model of the structure, e.g. by moulding or electroplating. The model is produced by micromechanically working a material that is suitable in this respect, wherein the three-dimensional structure and/or the configuration of the model is chosen to correspond to the desired component-associated surface parts, electric conductor paths and/or other electric and/or electronic circuits.
According to a second method, at least that part of the die or mould which corresponds to the component is produced by micromechanically working directly a material that is suitable in this respect, and the three-dimensional structure of the die or mould is made complementary to desired component-associated surface parts, electric conductor paths and/or other electric and/or electronic circuits.
The original shape or structure on which the final three-dimensional structure is based may alternatively be obtained by, e.g., electron-beam lithography, thereby enabling the creation of necessary structure for building, e.g., diffractive optical elements.
As earlier mentioned, it is proposed in accordance with the invention that the component substrate is comprised of a polymeric material, but that the material suitable for said micromechanical working process is comprised of silicon or quartz. This enables the three-dimensional structure to be produced with the necessary precision by micromechanically working a material suitable to this end, and then replicating this structure with retained precision on a substrate that is economically advantageous, particularly in those instances when it is necessary for the component concerned to include physical measurements that result in a relatively large component.
According to the present invention, a thus produced three-dimensional structure can be further worked with the aid of different processes, such as lithographic processes, PVD processes, CVD processes, doping, ion-implantation processes, or etching processes, such as ion, chemical, or plasma etching processes.
According to one embodiment of the invention, these is applied a process at specific angles relative to the three-dimensional structure so as to obtain shadowing effects through which processed and non-processed surface regions are formed.
It is proposed in this respect that two or more application angles be used to form a pattern of mutually different processed regions.
Said further treatment or working processes may be comprised of a combination of one or more of the earlier described processes.
Examples of components that can be obtained through an adaptation of a method according to the present invention are, for instance, thermocouples, pressure sensors, electro-optical coupling units or a channel structure for a biochemical analyser. Examples of such components will be made more apparent in the following description of proposed embodiments.
Those advantages that are primarily afforded by a method according to the present invention reside in the ability to produce in a cost effective manner components whose manufacture require a three-dimensional structure that can only be obtained by a micromechanical working process and where the components include physical measurements that only permit one or a few components to be produced with each substrate plate when practising traditional techniques.
This method opens the possibility of producing components that have hitherto been considered too costly in relation to what the components can achieve. The method therewith also opens a completely new field for the manufacture of components that enables components to be produced that have hitherto never been produced. The method can thus provide a decisive breakthrough in the manufacture of many different types of component.
The present invention also provides the advantage of enabling the peripheral elements required by the component to be readily integrated therewith, such as additional components, electric conductor paths or mechanical elements such as snap-fastener means, outwardly projecting surfaces or recesses intended for mounting the component on a substrate surface.
The primary characteristic features of an inventive method are set forth in the characterising clause of the following Claim 1.